Re: Defining a foreign key with a duplicate column is broken

On Sat, Aug 9, 2014 at 12:13 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

>
> So I'm thinking you're right: we should rewrite this code so that only
> indexes having all columns distinct can match, thereby ensuring that there
> is only one possible interpretation of the equality semantics for the
> foreign key.
>
>
I've attached a patch which disallows these, though I was not quite sure
about the new error message since likely this is something that should be
backpacked? I wasn't sure on the policy for new translations in a minor
release.

The wording of the comment above the code which disallows the duplicate
column references could likely do with some meaningful explanation about
the reasons why we disallow these, I thought your words would be a bit
better at doing this so I didn't try very hard on that part.

Is this roughly what you had in mind?

Regards

David Rowley